1. Field of the Invention
The present invention relates to a monitoring control system having a plurality of networks different in security level.
2. Description of the Related Art
In a general monitoring control system, information from equipment to be monitored is detected by a temperature sensor, a pressure sensor, a position sensor, and other various types of sensors; information thereof is presented to an operating staff and/or an observer; and various types of driving devices such as a motor, a valve, a switch, and a hydraulic power unit are operated by the operation of the operating staff and/or the observer to control operation conditions of the equipment. Such a monitoring control system is used in a wide range of fields, for example, electric generating plants, chemical plants, power reception and distribution equipment, and water and sewerage.
A configuration shown in FIG. 5 is adopted as a typical example of such a monitoring control system.
In the drawing, the monitoring control system includes: equipment 1 to be monitored; various types of sensors 2 which detect temperature, pressure, position, and other operational information of the equipment 1; various types of driving devices 3 such as a motor, a valve, a switch, and a hydraulic power unit, which drive the equipment 1; and a monitoring control device 4 which monitors operation conditions of the equipment 1 based on information from the sensor 2 to control to be desired conditions. The monitoring control device 4 has an operation terminal 4a which processes the information from the sensor 2 to drive the driving devices 3 and controls the equipment 1 to be desired conditions, and a display 4b which displays the operation conditions of the equipment 1; and these devices are mutually connected via a network 5 in facilities.
Furthermore in order to monitor the operation conditions of the equipment 1 at a location different from a placing location of the monitoring control device 4, a monitoring device 6 is provided via a network 8 and a plant gateway (hereinafter, gateway is referred to as G/W) device 7 connected to the network 5. The monitoring device 6 is provided with a communication terminal 6a which is for performing data communication with the monitoring control device 4 and a display 6b. Incidentally, these networks 5, 8 are mounted by a dedicated or general-purpose protocol.
In this case, ordinarily, in order to collect information from the external unit and to perform data transmission to the external unit, a device such as the monitoring device 6 that does not perform operating control of the equipment 1 is also capable of being connected to the Internet 10 via an outside communication G/W device 9.
In such a conventional monitoring control system, the equipment 1 and the monitoring control device 4 that directly operates operating of the equipment 1 are protected by setting a security level high by the plant G/W device 7 in order to prevent entering from the external unit, for example, a cyber attack. However, although the monitoring device 6, which merely monitors, secures security by the outside communication G/W device 9, the monitoring device 6 communicates with the external unit ; and therefore, security level cannot be maintained high so much.
Accordingly, in the conventional monitoring control system, the network 5 with a higher security level can prevent entering from the external unit via the Internet 10. However, the network 8 with a lower security level has a possibility that the entering from the external unit cannot be prevented in connection with upgrading of a recent cyber attack; and when the network 8 is once infected by a virus or the like, there arises a possibility of security threat in that the network 5 with the higher security level is also infected utilizing a packet allowed in the network 8.
By the way, generally, there is known one in which a device that evaluates security is provided in a network to restrict communication from a network with the lower security level. (Japanese Unexamined Patent Publication No. 2006-279338)
Furthermore, there is known one in which a communication direction is switched by an optical switch in order to protect information asset from a cyber attack from an outside network. (Japanese Unexamined Patent Publication No. 2004-274444)